Strange Sea creatures

Adaptations of creatures into monsters of dreams and mythology (and inspiration for films) can     teach us lessons, and provide new gifts or treasures. Dr Anjani Ganase asks us to look at some strange ocean creatures.

Living in the ocean requires a different set of skills from living on the land. On land most of us, with the exception of those with wings, are limited to moving around the earth’s surface. Most terrestrial animals spend their lifetimes crossing the terrain for food, water, shelter and mates. The ocean, however, has other properties: water allows organisms to move in all planes and connects animal and plant life at much greater and more intimate scales where water is also a medium of transport.

While the ocean is a 3D realm, it doesn’t make the ocean homogenous as there are natural physical barriers that limit movement and transport of marine life and material.  For example, the pressure exerted on our bodies increases with depth, owing to the weight of water above, and light only shines through the first 100 m of the water column, below which the rest of the ocean is a dark and mysterious abyss. The adaptations of marine life in the oceans seem alien to us, and at the same time fascinate us. We often refer to marine organisms, to draw ideas of what aliens may look like and to inspire “monsters”, which are essentially any creatures unknown to us. Yet, these strange and unusual traits are often simple adaptations to survive in ocean environments, to help with their survival. Here are a few “monstrous” traits that are used for survival.

Crown of Thorns Starfish in the Mariana Islands, Guam. Photo by David Burdick (NOAA photo library)

What organism can split into two at will or regenerate its limbs? Sea stars, similar to many other invertebrates, can split their body as a form of asexual reproduction. They replicate themselves by growing and dividing. This trait made the control of the Crown of Thorns starfish population on the Great Barrier Reef difficult in the beginning. Crown of Thorns are voracious predators to corals, and every so often, their populations reach outbreak levels following years of heavy flooding or nutrient pollution. These outbreaks would devastate reefs, as all of corals would be ravaged. Very quickly it was realized that the attempt to control the population by cutting up the sea stars, made the outbreak even worse as the populations were increasing instead of declining. Today, the Crown of Thorns starfish are injected with saline solution to kill them or the sea stars are simply removed from the coral reef, and taken out of the water.

 

A hagfish protruding from a sponge. California, Channel Islands, Santa Cruz

Photo courtesy NOAA Okeanos Explorer Program 

What creature can create up to 20 litres of slime while knotting itself up for a slippery escape? The hagfish is an ancient jawless fish that is closely related to lampreys and eels. They often scavenge the deep ocean, feeding on dead organisms. This makes them important in cleaning up the ocean of carrion and recycling nutrients. The slime of the hagfish is a keratin compound that is excreted and binds with the water to produce slime. Up to 20 litres of this slime can be produced at a time, more than enough to slip out of the jaws of a predator or clog their gills. Owing to the strength of the hagfish slime, it is now being researched for use as a biodegradable raw material.

What buries itself in the sand and waits for unsuspecting prey to swim by before reaching up to attack and pull the prey below the sand for a meal? The bobbit worm can grow up to a metre in length. It lunges at reef fish and crustaceans with its razor-sharp fangs. Their pharynx can turn inside out and armed with finger-like projections, it can pull prey into its mouth. The bobbit worm can also scavenge, moving along the reef at night eating anything in its path. They’re found on most tropical reefs, although its beautiful rainbow colours are rarely seen as they lie buried just below the sand. Fish have some defensive mechanisms against the bobbit worm: schools of fish can bombard it by squirting jets of water at it to reveal where it’s hiding under the sand. While these worms inspire scenes from the movie Dune, they are really no threat to humans.

Spawning aggregation of horseshoe crab. Photo courtesy Delaware National Estuarine Research Reserve

What has a large armoured plate, seven eyes, blue blood and breathes from its legs? The horseshoe crab is a living ancient that has been around for the last 450 million years (humans have only been around for 5 million years). The horseshoe crab resides in the shallow waters of the American and Asian coastlines. While they may look like relatives of crabs, they are more closely related to scorpions and spiders. Their closest relative – the sea scorpion - is now extinct. The blue blood of the horseshoe crab is incredibly important in the medical industry. The blood of horseshoe crabs is blue because of the presence of copper in the blood, which is used to form a compound called limulus amebocyte lysate (LAL) that is linked to the horseshoe’s adaptive immune response and survival. When there is an infection the compound surrounds the bacteria and coagulates as a defense response to remove the bacteria. Today, the blood of horseshoe crabs is used to detect bacterial contamination in vaccines and drugs and is therefore used by the pharmaceutical industry in quality control of medicines.

The more we discover about the ocean and the organisms that live there, the more we can learn how their traits can advance our society in technology and science. Let us view them as unknown resources with magical and mysterious, rather than monstrous, qualities.